The present invention relates to a filter device, which removes foreign matter contained in gaseous fuel supplied to an internal combustion engine, and a pressure regulator, which includes the filter device.
A pressure regulator as disclosed in Japanese Laid-Open Patent Publication No. 2010-167417 is provided in a supply passage through which gaseous fuel such as compressed natural gas (CNG) is supplied to an internal combustion engine. Such a pressure regulator includes a reducing valve, which reduces the pressure of the gaseous fuel, and a filter device, which removes foreign matter such as oil contained in the gaseous fuel.
The filter device includes a substantially cylindrical drain tank with a closed end. The body of the pressure regulator closes the opening of the drain tank. A cylindrical filter and a lid member arranged on the bottom of the filter are provided in the drain tank. The lid member includes a post, which extends downward. The lid member is supported by the bottom wall of the drain tank with the post. The lid member closes the bottom opening of the filter, and the body closes the top opening of the filter.
The gaseous fuel with the pressure reduced by the reducing valve flows through an inflow portion into the drain tank, passes through the filter, and then flows out of the drain tank through an outflow portion. The foreign matter caught by the filter when the gaseous fuel passes through the filter as described above is accumulated in the drain tank.
The pressure regulator is provided in an engine compartment. The body of the pressure regulator may receive thermal energy emitted from a thermal source such as an internal combustion engine provided in the engine compartment so that the body may be heated to a high temperature. When the body is heated to a high temperature as described above, the filter that is in contact with the body becomes high temperature as well. Accordingly, the filter may be deformed.
If the filter is shortened by such a deformation in the axial direction, a gap may occur in at least one of the interface between the filter and the body and the interface between the filter and the lid member. In this case, a part of the gaseous fuel that has flowed through the inflow portion into the drain tank may flow into the gap. The gaseous fuel that has flowed into the gap as described above flows out of the drain tank through the outflow portion without passing through the filter. Accordingly, if a gap occurs in at least one of the interface between the filter and the body and the interface between the filter and the lid member due to the deformation of the filter, the performance of the filter device for catching the foreign matter will be reduced.